Cyclonic Activity of Tropical Cyclones and Its Dynamics: A Single Continuous Process
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onic Activity of Tropical Cyclones and Its Dynamics: A Single Continuous Process M. I. Yaroshevich* Izvestiya Atmospheric and Oceanic Physics, Moscow, 119017 Russia *e-mail: [email protected] Received October 31, 2019; revised March 25, 2020; accepted April 1, 2020
Abstract—The possible effect of the cyclonic activity of tropical cyclones of one year on the cyclonic activity of the next year has been investigated. The dependence of the cyclonic activity of two time intervals of the beginning of the year on the cyclonic activity of similar time intervals of the end of the previous year is revealed. Based on the results, it is assumed that the dynamics of cyclonic activity at any time interval is a single continuous process. Keywords: tropical cyclones, cyclonic activity DOI: 10.1134/S0001433820050126
In studies, tropical cyclones are usually considered in two temporal intervals. The first is the time of the “life” of the cyclone and the second is the calendar year. The duration of the first interval is determined only by the process of the event, that is, by nature. The calendar year is logical and convenient in a number of statistical studies of tropical cyclones. However, it seems that the following question is worth asking: does the calendar year actually reflect a complete (i.e., from beginning to end) cycle of cyclonic activity? Of course, the dynamics of cyclonic activity is inherent in seasonality, the highest intensity of which occurs in the summer and autumn months of the year. But there are many cases when tropical cyclones occur in the winter and spring months. Therefore, it seems that the assumptions that the process of the formation of cyclonic activity is continuous and that there is only a time when the conditions are relaxed and conditions favorable for cyclonic activity appear to be valid in studies are acceptable. In this correspondence, an attempt is made to find out whether, in addition to the cycle of a separate tropical cyclone, there are more time intervals in which complete and completed cycles of cyclonic activity are realized. An analysis of the possibilities showed that, at least at the initial stage, these studies should not be carried out based directly on the chronological flow of tropical cyclones, but using a model for the integrated assessment of cyclonic activity over a given territory. This model of the representation of cyclonic activity has been repeatedly described and used [1, 2]. In general, it reflects the dynamics of cyclonic activity well
and has proven to be a relatively effective means of its research. Briefly recall the essence of the model. Here, in computational experiments, tropical cyclones of the northwestern part of the Pacific Ocean are considered. The basis of calculations is the method of estimating the kinetic energy of an individual cyclone, which is proportional to the square of the wind speed [3]. The coordinates of real cyclones given at 00:00 and 12:00 GMT are considered in the model as “sources” of wind and centers of circular wind fields1. The area wh
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